The use of wireless communication in today's environments is ubiquitous. It seems that everyone has at least one “smart” wireless device, such as a smart phone or tablet, and many have other types of mobile computing devices, such as laptops, notebooks, Chromebooks, etc., that support wireless communication. In addition to cellular and mobile computing, wireless communication technologies are used for other purposes, such as audio systems, portable telephone systems, screen casting, and peer-to-peer communication to name a few.
The most common wireless technologies include Wireless Wide Area Networks (WWAN) (e.g., LTE, HSPA+, UMTS, GPRS, generally associated with cellular networks), Wireless Local Area Networks (WLAN), including Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac standards (commonly referred to as Wi-Fi™ WLANs) and Wireless Personal Area Networks (WPAN), such as Bluetooth™. There are also wireless standards such as ZigBee™ that are used for Wireless Sensor Actor Networks (WSAN).
The radio frequency (RF) (radio) bands used by the various wireless networks can be generally classified into two categories: licensed, and unlicensed. Most cellular networks operate in licensed bands, while most WLANs, WPANs, and WSANs operate using unlicensed bands. Some common radio bands are collectively referred to as industrial, scientific, and medical (ISM) bands, which include operations at 2.4 GHz to 2.5 GHz (commonly referred to as 2.4 GHz or 2450 MHz bands), and 5.725 GHz to 5.875 GHz (commonly referred to as 5.8 GHz or 5800 MHz bands). ISM bands generally may be used for unlicensed operation, although there are some licensed users for some of these bands.
Substantially all of the forgoing wireless devices are or can be powered by rechargeable batteries. Conventional rechargeable battery chargers require access to a power source such as an alternating current (AC) power outlet, which may not always be available or convenient. There have recently been techniques introduced for so-called “wireless” charging using magnetic or inductive charging-based solutions in which the wireless device is placed in close proximity to the charging unit. However, during charging the wireless device must (generally) be placed on the charging base
Wireless power transmission at larger distances often use more advanced mechanisms, such as transmission via radio frequency (RF) signals, ultrasonic transmissions, and laser powering, to name a few, each of which present a number of unique hurdles to commercial success. Wireless power transmission systems (WPTS) employing RF signals may utilize portions of the licensed RF spectrum, including 2.4 GHz and 5 GHz radio bands. This presents a problem when operating in shared wireless medium environments under which other equipment and devices, such as WLAN access points and stations, are operating using the same or overlapping radio bands. In particular, transmission of wireless power signals in such shared wireless medium environments may interfere with data transmissions within WLANs. Accordingly, there is a need for solutions that enable a WPTS to coexist with existing equipment when operating in shared wireless medium environments. More generally, transmissions of signals using Physical Layers (PHYs) operating using the same or overlapping radio bands presents similar problems.
The examples provided herein of some prior or related systems and their associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following detailed description.